Capacitor goniometer compass



H es

/V VEN T095 Pou! F. Hoyner Thomos E. Woodruff ATTORNEY United States Patent O 3,264,554 y CAPACITOR GDNRMETER COMPASS Paul lF. Hay/ner, Lexington, Mass., and Thomas E. Woodrutf, Nashua, NH., assignors to Sanders Associates, Inc., Nashua, N .H., a corporation of Delaware Filed Apr. 16, 1964, Ser. No. 360,215 11 Claims. (Cl. 323-128) This invention relates to a method and apparatus for obtaining a true lbearing of an object with reference to magnetic north, by combining a magnetic compass and a goniometer, to shift the phase of a reference signal proportionally to the departure of the goniometer position from magnetic north as indicated by the compass.

As an example, as the goniometer is rotated clockwise from magnetic north (at which zero phase shift is introduced to 90, the phase shift introduced increases from to 90. Further rotation of the goniometer from 90 to 180 introduces a phase shift increasing to 180; still further rotation of 270 increases the phase shift to 270, and continued rotation to 360 increases the phase shift to 360 (zero). Similarly, counter-clockwise rotation of the goniometer introduces a phase shift decreasing 360 to 0 for one complete counter-clockwise revolution of the goniometer.

The method and apparatus described herein has many advantages over apparatus and methods heretofore known or used.

Among the objects of thi-s invention are the following:

To provide equipment of relatively small size, simple and easy to manufacture;

To provide such apparatus which eliminates residual torque on the compass;

To provide such equipment which will give a high signal-to-noise ratio;

To provide such apparatus in which no data smoothing of the output is required;

To provide equipment having iluid (liquid) damping preventing shock damage; and

To provide such apparatus in which the associated circuitry is quite simple; i.e., the output may be read by a phase meter.

Still other objects and advantages of this invention will be apparent from the specification.

The features of novelty which we believe to be characteristic of our invention are set forth with particularity in the appended claims. Our invention itself, however, both as to its fundamental principles and as to its particular embodiments, will best be understood by reference to the specification and accompanying drawing, in which FIG. 1 is a sectional view of a combined magnetic compass and goniometer according to this inventionv wherein the plates of FIGS. 2 and 3 are shown along section lines AA and B--B respectively;

FIG. 2 is a view of the cardioid plate employed in the goniometer-compass according to this invention; and

FlG. 3 is a view of the quadrant plates and associated capacitive coupling ring of the goniometer-compass according to this invention.

Referring now more particularly to FIG. 1, designates the hollow casing or housing of our combined goniometer-compass. The casing is shown diagrammatically, and it will lbe understood that it may be made in two parts, such as a cup-like bottom part and a lid secured to the top in any suitable manner (as by bolts) to form a tight enclosure.

The goniometer housing may, if desired, be provided with sighting rings and beads in case it is desired to take Visual bearings on distant objects, and will usually be mounted in gimbals and larranged for rotation in azimuth, as for instance, being mounted to rotate with a current meter, buoy, ship, or aircraft. If the magnetic compass Patented August 2, 1966 ice is provided with a compass card for visual reading, the top of the casing may be made transparent, and lubber lines may be marked.

Shaft 11 is provided, preferably coaxial with the housing and mounted in upper and lower bearings 12 and 13 respectively. Its lower end bears upon an end Ibearing as at 14 and its upper end 15 bears against bearing 16 which is backed by spring 59 for axial shock protection. The magnetic compass 9 is formed by a number (herein shown as four) of cylindrical magnets 17, 18, 19, and 20, carried on shaft 11 by nonmagnetic brackets or arms 24 and 25. The compass assembly, including card 26, is floated in tluid 60 such as Dow Corning Silicone DC200 liquid or a similar liquid. By oating the compass assembly as described, complete shock protection is achieved, and bearing friction on shaft 11 is reduced nearly to zero. A pressu-re chamber 27 having inlet holes (herein shown as four) 28, 29, 30 and 31, is preferably provided to permit expansion and contraction of the otation liquid.

The card 26 carries on its upper surface a cardioid conducting plate 34, joined by neck 3S to ring 36, and the lower side of the top casing is provided with four electrically insulated quadrant plates 40, 41, 42 and 43, each subten-ding an angle of from the axis of shaft 11. Four leads 50, 51, 52 and 53 are brought through the casing 10, and connected respectively to quadrant plates 40, 41, 42 and 43. These leads are supplied with a reference signal, for example of 15 kc., and the connection to plates 40, 41, 42 and 43 are phased 90 apart. Thus, plate 40 has a 90 phase angle, 41 has 180, 42 has 270, and 43 has 360 or 0.

The reference signal picked up by cardioid plate 34 is conducted to ring 36 connected to it, and is then transferred by capacitive coupling to ring 56, to which output lead 57 is connected. Lead 57 extends through casing 10 to the exterior of the casing and delivers the output signal to any associated circuitry or apparatus, such as a suitable phase meter.

The operation of our combined goniometer compass will now be described. It will be understood that the compass 9 remains xed in space as casing 10 is rotated in azimuth, being mounted to rotate with whatever it is attached to. Compass card 26, cardioid plate 34, its connecting neck 35, and ring 36 likewise remain fixed in space, being xed on shaft 11 to which the compass magnets 17, 18, 19 and 20 are fixed.

It will be remembered that quadrant plates 40, 41, 42

and 43 are provided with the reference signal displaced 90, 180, 270, and 360 or 0. If, when the casing comes to rest after having been rotated 90 from magnetic north, cardioid plate 34 will be exactly centered over quad-rant plate 40, and will pick, by capacity coupling, the reference signal with a 90 phase displacement. Similarly, for casing movements of 270, and 360 it will pick up the reference signal with 180, 270 and 360 phase displacement respectively. For an intermediate movement, it will pick up the reference signal with a phase displacement proportional to the rotation of casing 10. By applying the reference signal and the phase-displaced output signal to a phase meter, which may be calibrated in 360 from 0, the azimuth through which casing 10 has been rotated from north may be read directly in degrees.

Signal output voltages of as much as 10 volts can be obtained with a source capacity in the 50 to 100 pf. region, providing a high signal-to-noise ratio, even with audio frequency excitation across the goniometer.

In the foregoing we have described our invention and the best mode presently known to use for practicing the same, it should be understood that modifications and changes may be made, as Will be clear to those skilled in the art, without departing from the spirit and scope of our invention.

What is claimed is:

1. A goniometer compass comprising, 1n combination,

A. a housing,

B. a shaft mounted in said housing for rotation,

C. at least one compass magnet mounted on said shaft,

D. a cardioid-shaped conductor secured on said shaft,

E. a reference source of alternating potential,

F. :a plurality of equiangfular conducting elements mounted within said housing,

G. one or more of said elements having a capacitive relation to said cardioid plate,

H. said elements being connected to said reference source of alternating potential at points progressively differing in phase, and

I. means for conducting out vof said casing a voltage proportional to that on said cardioid plate.

2. A goniometer compass comprising, in combination,

A. a housing,

B. a shaft mounted in said housing for rotation,

C. a magnet mounted on said shaft,

D. a cardioid-shaped conductor secured on said shaft,

E. four quadrant conducting plates mounted wi'thin said housing and fed with a reference `oscillation progressively 90 displaced in phase,

F. said cardioid-shaped conducting element on said shaift being arranged for varying capacitive coupling .to said quadrant plates,

G. a first conducting ring c-onnected to said cardioid element,

H. a second ring capacitively coupled to said first ring,

and

I. a connection from said second ring to the exterior of said housing.

3. The combination claimed in claim 1 having said housing lled with flotation fluid.

4. The combination claimed in claim 3, said housing having an interior pressure chamber to permit expansion of said fluid.

5. The combination claimed in claim 1, said housing having an interior pressure chamber in its upper portion, one wall of said chamber being perforated.

6. The combination claimed in claimy 1 with means within said housing for reducing the .fbea-ring friction of said shaft to a minimum close to zero.

7. The combination claimed in claim 1 with means within said housing for providing shock protection, said means comprising a fluid oating the movable elements.

8. A capacity goniometer compass comprising, in combination,

A. ahousng,

B. a shaft mounted in said housing for rotation,

C. at least one compass -rna'gnet mounted on said shaft,

D. a conducting plate carried by said shaft,

E. a reference source of alternating potential,

F. a plurality of conducting elements mounted Within said housing and relatively xed thereto,

G. one or more of said elements being capacitively coupled to said conducting plate,

H. means connecting said conducting elements to said reference source of alternating potential at points progressively differing in phase, and

I. an loutput conductor connected Within said housing to a conductor capacitively coupled to said conducting plate.

9. A capacity goniometer compass comprising, in combination,

A. a housing,

. a shaft mounted in said housing for rotation,

. atleast one compass magnet mounted on said shaft,

. a conducting plate carried by said shaft,

. a reference source of alternating potential,

. conducting elements comprising four equispaced quadrant plates mounted within 'said housing and relatively fixed thereto,

G. one or more of said elements being capacitively coupled to said conducting plate,

H. means connecting said conducting elements to said reference source of alternating potential at points progressively differing in phase, and

I. an output conductor connected within said housing to a conductor capacitivel-y coupled to said conducting plate.

10. A capacity goniometer compass comprising, in

combination,

A. a housing,

B. a shaft mounted in said housing for rotation,

C. at least :one compass magnet mounted on said shafft,

D. a cardioid-shaped conducting plate carried by said shaft,

E. a reference source of alternating potential,

F. conducting elements comprising four equispaced quadrant plates mounted Within said housing and relatively fixed thereto,

F. one or more Iof said elements being capacitively colrpled to said conducting plate,

H. means connecting said conducting elements to said reference source of alternating potential at points progressively differing in phase, and

I. an output conductor connected within said housing to a lconductor capacitively coupled to said conducting plate.

11. The combination claimed in claim 9 in which said conducting plate is cardioid-shaped.

References Cited by the Examiner UNITED STATES PATENTS 2,634,316 4/ 1953 Breeze. 2,644,243 7/ 1953 Breeze et al. 317-246 FOREIGN PATENTS .826,733 1/ 1960 Great Britain.

LARAMIE E. ASKIN, Primary Examiner. JOHN F. BURNS, Examiner. E. GOLDBERG, Assistant Examiner. 

1. A GONIOMETER COMPASS COMPRISING, IN COMBINATION, A. A HOUSING, B. A SHAFT MOUNTED IN SAID HOUSING FOR ROTATION, C. AT LEAST ONE COMPASS MAGNET MOUNTED ON SAID SHAFT, D. A CARDIOID-SHAPED CONDUCTOR SECURED ON SAID SHAFT, E. A REFERENCE SOURCE OF ALTERNATING POTENTIAL, F. A PLURALITY OF EQUIANGULAR CONDUCTING ELEMENTS MOUNTED WITHIN SAID HOUSING, G. ONE OR MORE OF SAID ELEMENTS HAVING A CAPACITIVE RELATION OF SAID CARDIOID PLATE, H. SAID ELEMENTS BEING CONNECTED TO SAID REFERENCE SOURCE OF ALTERNATING POTENTIAL AT POINTS PROGRESSIVELY DIFFERING IN PHASE, AND I. MEANS FOR CONDUCTING OUT OF SAID CASING A VOLTAGE PROPORTIONAL TO THAT ON SAID CARDIOID PLATE. 